1. Field of the Invention
This invention relates to a surface processing method for processing the surface of an insulating article by ion injection and to a printer head provided in a printer configured for ejecting ink droplets to an article for printing to effect printing. This invention also relates to a substrate for a recording medium for supporting a signal recording layer of a recording medium.
2. Description of Related Art
For improving a variety of physical and chemical characteristics of an article being processed, such as hardness, elasto-plasticity, electrical conductivity, lubricating properties, durability, moisture-proofness, corrosion proofness, wettability or gas transmittance, there has been known a technique of implanting ions into the surface.
For implanting ions into the surface of an article being processed, there is a so-called ion beam implanting method of directly illuminating an ion beam on the article. However, the ion beam implanting method suffers from the problem that, if an article being processed has a three-dimensional structure, it is difficult to implant ions uniformly on the article surface.
For enabling uniform ion implantation on the article surface even if the article has a three-dimensional structure, there is proposed a technique of generating a plasma containing the ions to be implanted to implant the ions contained in the plasma into the article being processed. This technique is referred to below as a plasma implantation method.
In implanting ions by the plasma implantation method into the article, the article is placed in a plasma containing the ions to be implanted and a negative pulse voltage such as is shown in FIG. 1 is applied to the article. On applying the negative voltage to the article, the ions contained in the plasma are pulled into the article so that the ions are implanted on the article surface.
In the plasma implanting method, if the plasma containing the ions to be implanted is generated uniformly around the article being processed, the ions can be uniformly implanted on the article surface even if the article has a three-dimensional structure.
However, the above-described plasma implantation method is used exclusively for a case wherein the article to be processed is formed of an electrically conductive material, such as metal. The reason is that, if the article being processed is an insulating material, and ion implantation is executed by the plasma implantation method, electrical charges are accumulated in the article being processed, thus setting up what is called a charge-up state. If charge-up of the article being processed occurs in the plasma implantation method, the ions contained in the plasma cease to be pulled effectively into the article being processed. The result is that, if the plasma implantation method is applied to the insulating material, the process time is prolonged to render it difficult to improve the productivity.
It is therefore an object of the present invention to provide a surface processing method for an insulating material in which surface processing by ion implantation by the plasma implantation method can be realized effectively despite the fact that the article being processed is an insulating material. It is another object of the present invention to provide a printer head and a substrate for a recording medium each having on its surface a surface modified layer achieved as a result of ion implantation.
In one aspect, the present invention provides a surface processing method for an insulating material, in which ions are implanted in the insulating material to process its surface, including the steps of forming an electrically conductive thin metal film on the surface of the insulating material and applying a pulsed voltage containing a positive pulsed voltage and a negative pulsed voltage to the insulating material in a plasma containing ions to be implanted to implant ions in the surface of the insulating material.
In the surface processing method for an insulating material, according to the present invention, in which the bias voltage applied to the insulating material is a pulsed voltage containing a positive pulsed voltage and a negative pulsed voltage, there is no possibility of electrical charges being accumulated in the insulating material during the ion implantation. Since the electrically conductive thin metal film is formed on the surface of the insulating material, there is produced an electrical field in a direction perpendicular to the surface of the insulating material on application of the pulsed voltage. This implants ions in a direction perpendicular to the surface of the insulating material to realize effective ion implantation.
In another aspect, the present invention provides a printer head provided on a printer adapted to perform printing by ejecting ink liquid droplets towards a printing support, wherein a surface-modified layer modified in surface properties by ion implantation is formed on the surface of a liquid droplet ejecting portion adapted to eject the ink liquid droplets.
In the printer head of the present invention, in which the surface-modified layer is formed in its liquid droplet ejecting portion, it is possible to control the wettability to the ink of the liquid droplet ejecting portion and hence to prevent ink scorching or mixing of different sorts of inks in this liquid droplet ejecting portion.
In yet another aspect, the present invention provides a substrate for a recording medium adapted to support a signal recording layer of the recording medium, wherein a surface-modified layer modified in surface properties by ion implantation is formed on the surface of the substrate for the recording medium.
The substrate for the recording medium according to the present invention is improved in hardness or tenacity by provision of the surface-modified layer on its surface.
In the surface processing method for the insulating material according to the present invention, there is no risk of electrical charges from being accumulated in the insulating material despite the fact that ion implantation is executed on the insulating material. Since the electrically conductive thin metal film is formed on the surface of the insulating material prior to ion implantation, the ions are implanted in a direction perpendicular to the surface of the insulating material, so that ions may be implanted effectively even if the insulating material has a three-dimensional surface profile. The result is that ion implantation can occur on end effectively even if ions are implanted in the insulating material. This assures high-quality surface processing for an insulating material.
In the printer head according to the present invention, in which a surface-modified layer is provided in the liquid droplet ejecting portion, it is possible to control the ink wettability in this liquid droplet ejecting portion. This prevents ink scorching or mixing of different sorts of inks in the liquid droplet ejecting portion to improve the printing quality and operational reliability.
In the substrate for a recording medium, according to the present invention, in which a surface-modified layer is provided on its surface, it is possible to improve hardness and tenacity. Thus, by employing the substrate for a recording medium according to the present invention, a recording medium of high reliability may be provided which is reduced in flexure or deviation from surface planarity to cope with the tendency towards high recording density.